Heat oven to 350°F. Line a 9×13-inch pan with parchment and lightly grease.
Stir pretzel crumbs, graham crumbs, and brown sugar in a bowl.
Pour in melted butter and mix until evenly moistened and sandy.
Press the mixture firmly into the pan. Bake 8 minutes; set aside.
Warm condensed milk and peanut butter in a saucepan until smooth. Stir in vanilla and salt.
Spread the peanut butter mixture over the crust in an even layer.
Scatter chocolate chips, peanut butter chips, toffee bits, pretzels, and peanuts over the top.
Melt caramels with cream over low heat, stirring until glossy. Drizzle over the pan.
Bake 17 minutes more, until edges are set and top bubbles lightly.
Cool completely. Chill 30 minutes for cleaner cuts, then slice into bars.